Light source cooling body, light source assembly, a luminaire and method to manufacture a light source cooling or a light source assembly

ABSTRACT

A light source cooling body (100), a light source assembly, a luminaire and a method to manufacture a light source cooling body or a light source assembly are provided. The light source cooling body comprises a homogeneous body (104) made of a thermally conductive material. The homogenous body comprises an open space that comprises a wick structure, a condenser (112) and an evaporator (116). Near the evaporator the light source cooling body has an interface area (102) to thermally couple with a light source and to receive heat from the light source. The condenser is arranged away from the interface area. A portion 114 of the open space is tubular shaped. The open space may hold a cooling liquid partially in the gaseous phase and partially in the liquid phase and the wick structure is configured to transport the cooling material in the liquid phase towards the evaporator.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is the U.S. National Phase application under 35 U.S.C.§ 371 of International Application No. PCT/EP2015062634, filed on Jun.8, 2015, which claims the benefit of European Patent Application No.14177929.9, filed on Jul. 22, 2014. These applications are herebyincorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to the field of cooling bodies to which a lightsource may be coupled to cool the light source. The invention alsorelates to light source assemblies, luminaires, methods to manufacturesuch cooling bodies and methods to manufacture a light source assembly.

BACKGROUND OF THE INVENTION

Heat management is important in light sources, in particular when solidstate light emitters like Light Emitting Diodes (LEDs) are used as lightemitter. LEDs generate on a relatively small area a relatively largeamount of light and a relatively large amount of heat that must somehowbe conducted towards the environment. When a LED becomes too hot, theLED may become permanently damaged resulting in a non-functional lightsource. Several solutions have been proposed like providing thermalpaths via heat conductive materials towards a heat sink (whichcomprises, for example, cooling fins).

Published patent application US2008/0150126, which is incorporated byreference, discloses a Light Emitting Diode (LED) module with a heatdissipation device. The heat dissipation device includes a plurality ofheat spreaders each supporting at least one LED, includes a base thatsupports the heat spreaders and includes a heat pipe sandwiched betweenthe base and the heat spreader. The heat spreaders are thermallyconnected together via the heat pipe.

The heat dissipation device according to the cited prior art spreads theheat generated in the LEDs locally with the heat spreaders and uses theheat pipe to spread the heat along a larger space. The base is, forexample, a heat sink with cooling fins. The heat dissipation deviceprovides heat spreading such that the temperature of the LEDs is notbecoming too high. The cooling capacity of the heat dissipation deviceis limited by the amount of heat that can be transferred between thedifferent elements (LED-heat spreaders-heat pipe-base) and, finally, tothe environment. Furthermore, the cooling capacity of the base stronglydepends on manufacturing limitations of such a base—for example, withknown manufacturing technologies like extrusion or molding it is almostimpossible to manufacture cooling fins that provide an optimum between asize of a surface in contact with the environmental air, conduction ofheat by the fins, and space for environmental air to flow through thecooling fins. Thus, the heat dissipation device is capable of coolingLEDs, but has also limitations in its cooling capacity.

There is a tendency to increase the power of the LEDs and the heatdissipation device of the cited patent application lacks coolingcapacity for such high power LEDs.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a better cooling solutionfor a light source.

An aspect of the invention provides a light source cooling body. Afurther aspect of the invention provides a light source assembly. Anaspect of the invention provides a luminaire. Another aspect of theinvention provides a method of manufacturing a light source coolingbody. Yet a further aspect of the invention provides a method ofmanufacturing a light source assembly.

A light source cooling body in accordance with the first aspect of theinvention comprises a hollow space and an interface area. Substantiallythe whole light source cooling body is manufactured of the samethermally conductive material. The hollow space comprising anevaporator, a condenser and a wick structure. The open space isconfigured to hold a cooling material partially in a gaseous phase andpartially in a liquid phase. A wall of the open space is formed by thethermally conductive material. At least a portion of the hollow space istubular shaped. The wick structure is arranged to transport the coolingmaterial in the liquid phase towards the evaporator for being evaporatedin the evaporator when the evaporator receives heat. The wick structureis also manufactured of the thermally conductive material. The interfacearea is arranged the thermally coupled with a light source and toreceive heat from the light source. The interface area is an outer areaof the light source cooling body and is arranged in the direct vicinityof the evaporator and is separated by a thermally conductive wall fromthe evaporator for allowing heat of the light source to be transportedtowards the evaporator. The condenser is arranged away from theinterface area. Except the hollow space, the light source cooling bodyis a homogeneous body of the thermally conductive material. Theinterface area comprises a protrusion having a flat surface facing awayfrom the light source cooling body, wherein the flat surface beingconfigured to thermally couple to a surface of a light source.

Thus, the light source cooling body is a homogeneous body which impliesthat it does not comprise different materials between which transitioninterfaces exist. The transition interfaces may comprise air and, thus,they may each form a thermal barrier. The thermal path from theinterface area towards the evaporator is only through the thermallyconductive material and is not obstructed by transition interfacesbetween different materials. Thus, the heat generated in the lightsource that is thermally coupled to the interface area can easily flowtowards the evaporator to evaporate the cooling material (available inthe liquid phase) into in the gaseous phase. The cooling material in thegaseous phase can easily flow towards the condenser via the hollowspace. The condenser is away from the interface area and is consequentlyless warm than the direct environment of the interface area and theevaporator. Because of the lower temperature, in the condenser thecooling material may condensate thereby delivering heat from the lightsource to the environment of the condenser. Again, the condenser is onlysurrounded by the material of the light source cooling body and no othermaterials and/or transition interfaces prevent the transfer of heat fromthe cooling material in the gaseous phase to the material of the lightsource cooling body. Depending on the direct environment of the lightsource cooling body, the heat that is transferred to the material of thelight source cooling body (near the condenser) may be furthertransferred to the direct environment. For example, when the lightsource cooling body is surrounded, in the environment of the condenser,by air convection may lead to the delivery of heat to the environmentalair.

The above mechanism at least leads to a very good heat spreading withinthe light source cooling body. As such, when a light source in operationis thermally coupled to the interface area, temperature differences willbe relatively small between the temperature of the light source andspecific parts of the light source cooling body. Furthermore, becausethe temperature differences are relatively low, more heat can beconducted towards/provided to the direct environment of the light sourcecooling body. As such a good cooling mechanism is provided for the lightsource and a relatively good thermal management of a light sourceassembly or luminaire may be obtained when the light source cooling bodyis integrated in such a light source assembly or such a luminaire.

Furthermore, the fact that the light source cooling body is ahomogeneous body means that the light source cooling body is aone-piece-component. Thereby, compared to the known cooling solutions inwhich, for example, heat pipes are used, the amount of components isreduced and no specific assembling steps are required during theproduction of the light source cooling body. Thereby manufacturing costsare saved. Additionally, when the light source cooling body is made ofthe same thermally conductive material, additive manufacturingtechnologies may be used to manufacture the light source cooling body.Such technologies are, for example, direct metal laser sintering,selective laser sintering, electron beam melting, fused depositionmodeling, 3d printing based on extrusion and additive manufacturingbased on using arc wires. In general, in an additive manufacturingtechnology, the component is build up in layers. Subsequently, when suchadditive manufacturing technologies are used, one can easily optimizethe shape of the light source cooling body and the shape of the hollowspace. Traditionally, when heat pipes are used, the number of bends thatcan be made in the heat pipes are limited because it would damage theinternal structure of the heat pipe too much, while with additivemanufacturing the internal structure may be optimized at everyposition—for example, the shape of the hollow space may be optimized.

Please note that the evaporator is arranged near the interface area andthe condenser is arranged away from the interface area. This means thatthe evaporator is arranged closer to the interface area than thecondenser.

The hollow space forms a (regular non-loop) heat pipe or a loop heatpipe wherein the wick is provided to transport the cooling material inthe liquid phase towards the evaporator. A pressure of the coolingmaterial in the gaseous phase allows the transport of the coolingmaterial from the evaporator to the condenser. The wick provides via acapillary action the transport in the opposite direction. When thehollow space forms a loop heat pipe, the wick is located close to and/orpartially in the evaporator to transport the cooling material from theend of the loop (or a liquid reservoir) into the evaporator. When thehollow space is a regular (non-loop) heat pipe, the wick will extendfrom the condenser up to (into) the evaporator. The wick may comprisegrooves, arteries, porous sponge-like structure, mesh-like structure togenerate sufficient capillary pressure for transporting the coolingmaterial in the liquid phase to an area of the evaporator where thecooling material evaporates when heat is received by the evaporator.

As discussed above, the interface area comprises a protrusion having aflat surface facing away from the light source cooling body, wherein theflat surface being configured to thermally couple to a surface of alight source. For example, when the light source is a solid state lightemitter, a flat contact area to the solid state light emitter isadvantageous because solid state light emitters have in general a flatsurface configured to be coupled to another component. The fact that theinterface area comprises a protrusion creates possibilities to providearound the protrusion “lowered” electrical connections for providingpower to the light source. When the solid state light emitter is coupledwith its lower surface to the protrusion one may the “lowered”electrical connections to connect to the lower surface of the solidstate light emitter. In particular the protrusion allows the use ofso-termed flip-chip LEDs which have at least at one of their surfaces alight exit window through which light is emitted in the ambient andwhich have at a surface opposite the light exit window power contactareas by which the flip-chip LED has to be connected to power lines,such as the “lowered” electrical connections. The protrusions provide agood thermal path to the evaporator because they are part of thehomogeneous body of the light source cooling body and the flip-chip LEDsmay extends, in a plane defined by the flat surface, beyond theprotrusion. In the area that they extends beyond the protrusion contactareas may be provided on the flip-chip LEDs for begin connected to powerlines. In other words, the protrusion provides an advantageous way ofcoupling light sources to the light source cooling body when the lightsource has a light exit window at a top surface and has at a bottomsurface (opposite the top surface) electrical contact—the bottom surfacemay be coupled to the protrusion and at least a portion of the bottomsurface with the electrical contacts may extend beyond the protrusionsuch that the electrical contacts may be coupled to powerlines.

When the light source cooling body is suitable for coupling a pluralityof light sources to, the interface area comprises a plurality ofcorresponding protrusions. It is to be noted that the protrusion, or inspecific embodiments, the protrusions are well thermally coupled to theevaporator. For example, the protrusions start at the wall of theevaporator and extends away from the evaporator. Optionally, theinterface area and/or the protrusion(s) comprise fasteners for fasteningthe light source to the interface area. Another advantage of usingprotrusions is that the light source that is coupled to the protrusionis arranged at a short distance above the surface of the light sourcecooling body and may emit light in an angular range that is larger than180 degrees. Because the light source cooling body can be manufacturedby means of an additive manufacturing method, the wick structure can beoptimized. For example, when the hollow space is a tube that has bendsor is partially circular, the wick structure can be optimized for suchbends such that the capillary action is still optimal. This is notpossible with the known heat pipe structures which are made as astraight pipe and bended afterwards thereby damaging the wick structureand reducing its capillary action.

Optionally, the thermal conductivity of the thermal path from theinterface area towards the evaporator is larger than 3 W/mK. Optionally,the thermal conductivity of the thermal path from the interface areatowards the evaporator is larger than 30 W/mK.

Optionally, the hollow space is at least partially tubular shaped. Forexample, the hollow space comprises a tube connecting the condenser withthe evaporator.

Optionally, the hollow space also comprises a sealable opening to theoutside of the light source cooling body. The sealable opening may beused for pumping air out of the hollow space and for providing thecooling material into the hollow space.

Optionally, the light source cooling body comprises the cooling materialpartially in the liquid phase and partially in the gaseous phase and,when a sealable opening is provided, the sealable opening is liquid andgas tightly sealed.

Optionally, the light source cooling body further comprising coolingfins for providing an interface area to ambient/environmental air. Thecondenser being arranged near the cooling fins for obtaining awell-thermally conductive path from the condenser to the cooling fins.The cooling fins are also a part of the homogeneous body of thethermally conductive material. In other words, the cooling fins are anintegral part of the light source cooling body.

The cooling fins are part of the interface of the light source coolingtowards the environment. The cooling fins provide a relatively largeinterface area to the environment of the light source cooling body and,as such, a lot of heat can be provided to the environment. Thereby a lotof heat can be conducted away from the light source to the environmentvia the hollow space and, thus, the light source is well cooled. Becausethe cooling fins are also an integral part of the homogeneous lightsource cooling body, no additional interfaces (which might comprise airor other thermally isolating materials) are present in the thermal pathfrom the condenser towards the cooling fins, and, thus, a relativelylarge amount of heat can be transported to the cooling fins.

Optionally, the thermal conductivity of the thermal path from thecondenser towards the cooling fins is larger than 3 W/mK. Optionally,the thermal conductivity of the thermal path from condenser towards thecooling fins is larger than 30 W/mK.

Optionally, the light source cooling body comprises a heat sinkinterface area being arranged to thermally couple a heat sink to andconfigured to provide heat to the heat sink. The heat sink interfacearea is a further outside area of the light source cooling body arrangedclose to the condenser and may optionally comprise connector elementsfor connecting a heat sink to the heat sink interface area. The heatsink interface may be provide in addition to, or alternatively to, thecooling fins.

Optionally, a shape of the light source cooling body (and when the lightsource cooling body also comprises cooling fins, optionally also theshape of the cooling fins), is selected to allow a transmission or lightgenerated by a light source provided on the interface area towards anambient of the light source cooling body. Thus, in other words, theshape of the light source cooling body is specifically design for thepurpose of lighting applications. It might be that parts of the lightsource cooling body receive (and optionally absorb) light from the lightsource provided on the interface area, but at least a large portion ofthe generated light (for example, more than 70%) is emitted into theambient of the light source cooling body. Optionally, parts of the lightsource cooling body that receive light from the light source provided onthe interface area are at least partially reflective such that a largeportion of the light impinging on those parts is reflected (for example,more than 70%). These optional embodiments prevent that the light sourcecooling body introduces optical inefficiency and it is prevented thatthe light source cooling body is heated by absorbed impinging lightthereby introducing thermal inefficiency.

Optionally, a thickness of a thermally conductive wall between theinterface area and the evaporator is thinner than 2 millimeter. Thus,when, from the evaporator towards the interface area, a shortestthickness of the thermally conductive material is measured, themeasurement should reveal that the thickness is less than 2 millimeter.Such a relatively thin thermally conductive wall provides a shortthermal path from the interface area to the evaporator and, thus, athermal path of a high thermal conductivity. When the interface areacomprises one or more protrusions, the protrusions are also part of thethermally conductive wall. Optionally, the thickness of the thermallyconductive wall is thinner than 1.5 millimeter. Optionally, thethickness of the thermally conductive wall is thinner than 1 millimeter.

Optionally, the wall of the hollow space is at least partially coveredwith the wick for transporting the cooling material in the liquid phasefrom the condenser towards the evaporator. Optionally, the wick extendsat least partly in evaporator. Optionally, the wick extends at leastpartially in condenser. Optionally, the wick is provided at leastpartially in hollow space between evaporator and condenser. Thisoptional embodiment applies to the above discussed “regular” (non-loop)heat pipe.

Optionally, the hollow space forms a loop in which a vapor channel isprovided from the evaporator towards the condenser and a liquid channelis provided from the condenser to the evaporator, the wick beingarranged to receive cooling material in the liquid phase from the liquidchannel or a liquid reservoir being fed by the liquid channel and thewick at least extends into the evaporator. This optional embodimentrelates to a loop heat pipe.

In embodiment, the presence of the wick structure in the hollow space isnot necessary. If no wick structure is present, and if the hollow spaceis tubular shaped and is arranged in a meandering configuration, whereinthe tubular shaped hollow space meanders a plurality of times betweenthe condenser and the evaporator. This optional embodiment relates to apulsating heat pipe—such a heat pipe does, in general, not have a wickstructure. Optionally, the meandering tubular hollow space may also forma loop. A radius of the tubular shaped hollow space is selected suchthat a good capillary action can be obtained. Often, the tubular shapedhollow space has turns in at the condenser and also at the evaporator.In use, the tubular shaped hollow space comprises locally at severallocations some cooling material in the liquid phase and the relativesmall portions of liquid cooling material are separated from each otherby cooling material in the gaseous phase. More information about thistype of heat pipes can be found in the article “Closed and open looppulsating heat pipes” of Sameer Khandekar, et al, published in theproceedings of “13^(th) International Heat Pipe Conference” Shanghai,China, Sep. 21-25, 2004. The cited article is incorporated by reference.

Optionally, the thermally conductive material comprising at least one ofAluminum, Copper, Magnesium, Iron, Nickel, CrNi steel, Carbon steel, aCopper-Zinc alloy, a Copper-Tin alloy, a thermally conducive plasticmaterial, and a thermally conductive ceramic material such as AluminumNitride, Aluminum Oxide, Beryllium Oxide, Boron Nitride, SiliconCarbide, Titanium Oxide, Magnesium Oxide, Zinc Oxide, Silicon Nitride,Zirconium Oxide, Tungsten Carbide, and mixes thereof. Examples ofthermally conductive plastics relate to a combination of a matrixpolymer of Liquid Crystal Polymer (LCP), Poly p-Phenylene Sulfide (PPS),Poly Amide (PA), Poly Propylene (PP) (crystalline or semi-crystalline),Poly Carbonate (PC) (amorphous), Poly Butylene Terephthalate (PBT), andPoly Ethylene Terephthalate (PET) with filler materials like BN or withgraphite filler materials.

Optionally, the cooling material comprising at least one of Water,Acetone, Ammonia, Methanole and Ethanole. For example, when thethermally conductive material comprises Aluminum, the cooling materialoften comprises Acetone. For example, when the thermally conductivematerial comprises Copper or Nickel, the cooling material oftencomprises Water.

Optionally, the light source cooling assemblies according to the abovediscussed embodiments is obtainable by an additive manufacturingtechnology. Examples and advantages of additive manufacturingtechnologies are discussed before.

According to another aspect of the invention, a light source assembly isprovided which comprises a light source cooling body according to one ofthe above discussed embodiments and which comprises a light sourceprovided on and thermally coupled to the interface area of the lightsource cooling body.

Optionally, the light source assembly further comprises electricconductors being provided on and isolated from the light source coolingbody for providing electrical power to the light source. For example,dielectric tracks are provided on the light source cooling body andelectrically conductive tracks are provided on the dielectric tracks.The electric conductive tracks may have at the interface area connectionareas for electrically connecting the light source to. The manufacturingof the dielectric material and the electrically conductive material isbased on a manufacturing technology wherein layers are manufactured ontop of a three dimensional object. For example, the dielectric materialand the electrically conductive material may both also be provided onthe light source cooling body by means of an additive manufacturingtechnology. An example of a suitable additive manufacturing technologyare printing technologies that are configured to printing layers on 3dobjects.

Optionally, when the light source cooling body comprises cooling fins asan integral part of the light source cooling body, a portion of thecooling fins are also arranged as an optical element for influencing, inuse, a light beam emitted by the light source assembly. For example, theportion of the cooling fins may form a reflector, a collimator, a slatcollimator, etc. In such embodiments, the light source cooling body isoptionally made of a light reflective material, or the cooling fins areprovided with a layer of a light reflective material.

Optionally, the light source comprises a solid state light emitter suchas a Light Emitting Diode (LED) or a laser diode. The light source maybe a solid state light emitter package, such as a LED provided on aprinted circuit board or packaged in any other way. The light source mayalso comprises a plurality of solid state light emitter dies. The lightsource assembly is, however, not limited to solid state light emittersonly.

Optionally, the light source is a flip chip Light Emitting Diode beingprovided on the protrusion, a light exit window of the flip chip LightEmitting Diode faces away from the flat surface of the protrusions, theflip chip Light Emitting Diode has an opposite surface opposite thelight exit window, a portion of an opposite surface is provided on theflat surface and another portion of the opposite surface extends beyondthe protrusion and comprises electrical contact areas.

According to an aspect of the invention, a luminaire is provided whichcomprises a previously discussed embodiment of a light source coolingbody or which comprises a previously discussed embodiment of a lightsource assembly.

According to a further aspect of the invention, a method ofmanufacturing a light source cooling body is provided. The methodcomprises receiving a three dimensional model of a light source coolingbody that comprises i) a hollow space comprising an evaporator and ancondenser, the hollow space being configured to hold a cooling materialpartially in a gaseous phase and partially in a liquid phase, a wall ofthe hollow space being formed by the thermally conductive material, atleast a portion of the hollow space is tubular shaped, the hollow spacefurther comprising a wick for transporting the cooling material in theliquid phase towards the evaporator for being evaporated when theevaporator receives heat; ii) an interface area being arranged tothermally couple a light source to and configured to receive heat fromthe light source, wherein a) the interface area being arranged in adirect vicinity of the evaporator and being separated by a thermallyconductive wall from the evaporator for allowing heat of the lightsource to be transported towards the evaporator, b) the condenser beingarranged away from the interface area where the light source coolingbody has an interface to an environment of the light source coolingbody, and c) except the interface area, the light source cooling bodybeing a homogeneous body of the thermally conductive material. Themethod further comprises building up the light source cooling body of athermally conductive material by depositing layers on top of each otherby means of an additive manufacturing technology according to thereceived three dimensional model of the light source cooling body.

Examples of additive manufacturing technologies are, for example, directmetal laser sintering, selective laser sintering, fused depositionmodeling, 3d printing based on extrusion and additive manufacturingbased on using an arc wire. When such additive manufacturingtechnologies are used, one can easily optimize the shape of the lightsource cooling body and the shape of the hollow space. Traditionally,when heat pipes are used, the number of bends that can be made in theheat pipes are limited because it would damage the internal structure ofthe heat pipe too much, while with additive manufacturing the internalstructure may be optimized at every position—for example, the shape ofthe hollow space may be optimized. Also, the above manufacturing methodbuilds up the light source cooling body as a homogeneous component madeof (optionally) one material. Thereby it is ensured that no interfacesare present in the light source cooling body with a relatively highthermal resistance. Thus, the manufacturing technology enables themanufacturing of light source cooling bodies which provide a bettercooling of a light source. In an optional embodiment, the light sourcecooling body that is build up in layers is sintered afterwards.

According to another aspect a method of manufacturing a light sourceassembly is provided which comprises the above discussed method ofmanufacturing a light source cooling body and which at least comprisesthermally coupling a light source to the interface area of themanufactured light source cooling body.

Optionally, the method of manufacturing a light source assembly alsocomprises i) manufacturing dielectric tracks of dielectric material onthe light source cooling body, the dielectric tracks extending towardthe interface area of the light source cooling body, ii) manufacturingpower tracks of an electrically conductive material on the isolationtracks and providing connection areas (as part of the power tracks) atthe interface area, the connection areas are for coupling the lightsource to, and iii) electrically connecting the light source coupled tothe interface area to the connection areas. The manufacturing of thedielectric tracks and the power tracks may also be performed by anadditive manufacturing technology. This may be the same additivemanufacturing technology as used for manufacturing the light sourcecooling body but, alternatively, this may also be another additivemanufacturing technology that is suitable for manufacturing thedielectric tracks and/or the power tracks. It might be that the threedimensional model of the light source cooling body also comprisesinformation about the locations where the dielectric tracks and powertracks must be manufactured. This information may also be received inand used by the method of manufacturing a light source assembly.

These and other aspects of the invention are apparent from and will beelucidated with reference to the embodiments described hereinafter.

Further preferred embodiments of the device and method according to theinvention are given in the appended claims, disclosure of which isincorporated herein by reference.

It will be appreciated by those skilled in the art that two or more ofthe above-mentioned options, implementations, and/or aspects of theinvention may be combined in any way deemed useful.

Modifications and variations of the light source cooling body, themethod of manufacturing the light source cooling body and/or themanufacturing of a light source assembly which correspond to thedescribed modifications and variations of the light source cooling body,can be carried out by a person skilled in the art on the basis of thepresent description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 schematically shows a light source cooling body according to theinvention,

FIG. 2a schematically shows a top-view of an embodiment of a lightsource assembly comprising a light source cooling body,

FIG. 2b schematically shows a cross-sectional view of the embodiment ofFIG. 2a along line II-II′,

FIG. 3a schematically shows a top-view of another embodiment of a lightsource assembly comprising a light source cooling body,

FIG. 3b schematically shows a cross-sectional view of the embodiment ofFIG. 3a along line III-III′,

FIG. 4a schematically shows a three dimensional view of a furtherembodiment light source assembly comprising a light source cooling body,

FIG. 4b schematically shows a cross-sectional view of the furtherembodiment of FIG. 4a along line IV-IV′,

FIG. 5a schematically shows a light source assembly embodied in a lamp,

FIG. 5b schematically shows a luminaire,

FIG. 6 schematically shows a method of manufacturing a light sourcecooling body and a method of manufacturing a light source assembly,

FIG. 7a schematically shows an embodiment of a light source assembly,and

FIG. 7b schematically shows a cross-sectional view of the embodiment ofFIG. 7a along line VII-VII′.

It should be noted that items denoted by the same reference numerals indifferent Figures have the same structural features and the samefunctions, or are the same signals. Where the function and/or structureof such an item have been explained, there is no necessity for repeatedexplanation thereof in the detailed description.

The Figures are purely diagrammatic and not drawn to scale. Particularlyfor clarity, some dimensions are exaggerated strongly.

DETAILED DESCRIPTION

FIG. 1 schematically shows a light source cooling body 100 according tothe invention. The light source cooling body 100 comprises a homogeneousbody 104 of a single material that is thermally conductive. Inside thehomogeneous body 104 is provided a hollow space that is formed in theexample of FIG. 1 by spaces 112, 114 and 116. The hollow space mayoptionally comprise a small channel 120 to the outside surface of thelight source cooling body 100 such that at the outside surface of thelight source cooling body 100 is provided a sealable opening that may beused to pump the hollow space empty and provide a cooling material intothe hollow space. The walls of the hollow space are formed by thematerial of the homogeneous body 104. Thus, no additional materials areprovided in between the hollow space and the homogeneous body 104. Space116 is configured as an evaporator in which a cooling material presentin a liquid phase and which is evaporated when heat is received by theevaporator 116. The evaporator 116 is positioned close to an interfacearea 102 at which a light source may be thermally coupled to the lightsource cooling body such that heat can easily flow from the light sourcetowards the evaporator 116. The thermal path between the interface area102 and the evaporator 116 is short and has a low thermal resistance.Space 112 is a condenser in which the cooling liquid in the gaseousphase condenses when the environment of the condenser 112 absorbs heatfrom the condenser 112. The condenser 116 is not located close to theinterface area 102, but is positioned away from the interface area 102at an area of the light source cooling body 100 where the light sourcecooling body 100 has an outside area that is capable of providing heatto the environment of the light source cooling body 100. Space 114 is atubular space through which the cooling material, in the gaseous phaseand the liquid phase, can be exchanged between the evaporator 116 andthe condenser 112. Space 114 may also have a different shape.

The sealable opening 122 may be sealed by, for example, a glass fritthat is compatible with the thermally conductive material of thehomogeneous body 104 such that a gas and liquid tight seal seals thesealable opening 122. The sealable opening 122 may also be sealed by alow temperature metal composition, such as low temperature solders (forexample, SnAgBi). Also the material of the light source cooling body 100immediately around the sealable opening 122 may be heated with a lasersuch that the sealable opening is closed by the thermally conductivematerial of the light source cooling body 100 itself. In particular,immediately after air is pumped out of the hollow space and the coolingmaterial is provided into the hollow space, the sealable opening issealed. In other embodiments, the sealable opening 122 is closed bypunching or pinching off the sealable opening 122. Pinching off is inparticular useful when the sealable opening 122 is provided in a smalltube protruding out of the homogeneous body 104.

In FIG. 1 the evaporator 116 and condenser 112 are schematicallypresented as box-shaped areas. Real embodiments of the evaporator 116and condenser 112 may have different shapes. In an embodiment the wholehollow space is tubular shaped and a portion of the tubular shapedhollow space that is close to the interface area is termed the“evaporator” and a portion of the tubular shaped hollow space that is inan portion of the light source cooling body where the light sourcecooling body can easily provide heat to the environment is termed the“condenser”.

In FIG. 1 the light source cooling body 100 is drawn as a box-shapedbody. Other shapes are also possible—for example, the light sourcecooling body 100 may also be a disk shaped or (solid) cylindrical shapedobject. At least is the shape of the light source cooling body 100 incombination with the location of the interface area 102 selected suchthat, when a light source is provided on the interface area 102, lightgenerated by the light source can easily be transmitted into the ambientof the light source cooling body 100. A portion of the light generatedby the light source cooling body 100 may impinge on portions of thelight source cooling body 100 and then these portions may be relativelysmall or these portions are at least partially light reflective.

The material of the light source cooling body is at least thermallyconductive which means that its thermal conductivity is at least 3 W/mK.In an advantageous embodiment, the thermal conductivity is higher, e.g.larger than 30 W/mK Hereinafter, in table 1, useful materials areprovided.

TABLE 1 thermal conductive materials to be used in the light sourcecooling body Thermal conductivity Material At 20° C. Metals Cu Copper400 W/mK Al Aluminum 100-240 W/mK Mg Magnesium 70-150 W/mK Ni Nickel 90W/mK Fe Iron 16 W/mK CrNi steel 16 W/mK Carbon steel 50 W/mK CuZn Brass110 W/mK CuSn Bronze 100 W/mK CuSn4P Phosphor Bronze Ceramics AlNAluminum Nitride 80-260 W/mK Al₂O₃ Aluminum Oxide 18-36 W/mK BeOBeryllium Oxide 184-300 W/mK BN Boron Nitride 15-600 W/mK SiC SiliconCarbide 60-210 W/mK TiO₂ Titanium Oxide 11.7 W/mK MgO Magnesium Oxide40-60 W/mK ZnO Zinc Oxide 35 W/mK Si₃N₄ Silicon Nitride 20 W/mK ZrO₂Zirconium Oxide 3 W/mK WC-Co Tungsten Carbide 85 W/mK

Optionally, the thermal conductive material of which the light sourcecooling body 100 is manufactured, comprises a thermally conductiveplastic with a thermal conductivity that is larger than 3 W/mK. Examplesare a matrix polymer of Liquid Crystal Polymer (LCP), Poly p-PhenyleneSulfide (PPS), Poly Amide (PA), Poly Propylene (PP) (crystalline orsemi-crystalline), Poly Carbonate (PC) (amorphous), Poly ButyleneTerephthalate (PBT), and Poly Ethylene Terephthalate (PET) with fillermaterials like Boron Nitride, to reach thermal conductivities up to 10W/mK (electrically insulating) or even 40 W/mK (electrically conductive)with graphite filler materials.

The cooling material that may be provided is, for example, Water,Acetone, Ammonia, Methanole or Ethanole. Specific cooling materials arewell suitable for use in combination with a specific thermallyconductive material of which the light source cooling body 100 ismanufactured. When the thermally conductive material comprises Aluminum,the cooling material may comprise Acetone. When the thermally conductivematerial comprises Copper or Nickel, the cooling material may compriseWater.

In an embodiment of the light source cooling body 100, the hollow space112, 114, 116 is provided with the cooling material and the opening 122is gas and liquid tightly sealed.

In an embodiment, the thermal conductivity of the (shortest) thermalpath from the evaporator 116 to the interface area 102 is at least 3W/K. This thermal conductivity is determined by the (shortest) length ofthe thermal path from evaporator 116 to the interface area 102 and thethermal conductivity of the material of which the light source coolingbody is manufactured.

The light source that may be coupled to the interface area 102 may beany light source. In specific embodiments of the light sources, thelight source may be a solid state light emitter or a solid state lightemitter package. Embodiments of solid state light emitters at leastinclude Light Emitter Diodes and Laser Diodes. One solid state lightemitter package may include one or more solid state light emitters.Optionally, one or more light source may be coupled to the interfacearea 102.

Specific examples of the light source cooling body 100 are provided inthe subsequent figures. Details of the above discussed light sourcecooling body 100 also apply to subsequent embodiment unless it isexplicitly stated that a specific feature has another implementation.

FIG. 2a schematically shows a top-view of an embodiment of a lightsource assembly 200 comprising a light source cooling body. The lightsource assembly comprises the body 104 of the light source cooling bodyin which a hollow space 210 is provided. In FIG. 2a it has beenindicated that an area referred to with 216 is the evaporator 216 of thehollow space and that the areas 212, 212′ are the condensers 212, 212′.On an outside surface of the body 104 is provided an interface area 202to which a solid state light emitter 250 is thermally coupled. In use,heat generated in the solid state light emitter 250 is transferredthrough the thermally conductive material of the body 104 towards theevaporator for evaporating within the evaporator a cooling material inthe liquid phase. As shown in FIG. 2a , the evaporator 216 is arrangedin the direct vicinity of the interface area 202. The condensers 212,212′ are arranged away from the interface area 202. The portions of thebody 104 that enclose the condensers 212, 212′ are able to absorb heatfrom the condenser 212, 212′ and, optionally, are able to provide theheat towards the environment of the light source assembly 200.

An optional element of the light source assembly 200 is also drawn inFIG. 2a , namely electrical conductive tracks 260 which are provided onthe body 104 and are electrically isolated from the body 104. Theelectrical conductive tracks 260 follow a path towards the interfacearea 202 for providing power to the solid state light emitter 250. Ascan be seen in a subsequent figure, the solid state light emitter 250 iselectrically coupled to the electrical conductive tracks 260.

FIG. 2b schematically shows a cross-sectional view of the embodiment ofFIG. 2a along line II-II′. FIG. 2b presents three cross-sectional viewsof the hollow space 210. The hollow space 210 is tubular shaped and,thus, the cross-sections are circular.

At the wall of the hollow space 210 is provided a wick 211. A wick 211is a structure that provides a relatively large capillary pressure andis configured to transport cooling material in the liquid phase from thecondenser towards the evaporator. The wick structure is alsomanufactured of the thermally conductive material of the body 104 andis, in practical embodiments, also in contact with the body 104 (e.g. toreceive heat from or provide heat to the body 104). The wick 211 maycomprise grooves, arteries, porous sponge-like structure, mesh-likestructure to generate sufficient capillary pressure for transporting thecooling material in the liquid phase to an area of the evaporator wherethe cooling material may evaporate when heat is received by theevaporator. The presented hollow space 210 with the wick 211 togetherform a (regular non-loop) heat pipe.

In an embodiment, the wick 211 may comprise in between the evaporator216 and the condensers 212, 212′ channels for transporting a liquid andwithin the evaporator 216 and the condensers 212, 212′ the channels areperforated to, depending on the specific space in which they areprovided, to provide liquid or to receive liquid.

It is further shown in FIG. 2b that the interface area 202 is, in theembodiment of FIGS. 2a and 2b , a protrusion 202′ that extends away fromthe evaporator 216 and extends out of the body 104. On a surface of theprotrusion 202′, which is a surface that faces away from the body 104,is provided the solid state light emitter 250. That surface is flat suchthat the solid state light emitter 250 can be well-thermally coupled tothat surface. In other embodiments, when the light source is not flat,the surface of the protrusion may has a shape that corresponds to theshape of the light source. In between the protrusion 202′ and the lightsource 250, a specific thermally conductive glue or thermally conductivepasta may be present for fastening the light source 250 to theprotrusions 202′. The solid state light emitter 250 (or other types oflight sources) may also be coupled to the interface area 202 by means offastening element (not shown).

In FIG. 2b it is also shown that the electrical conductive tracks 260are provided on a dielectric track 258 such that they are wellelectrically isolated from the body 104. The light source 250 is, forexample, soldered to the electrical conductive tracks 260—as shown inFIG. 2b , some soldering material 262 may be present between theelectrical conductive track 260 and the solid state light emitter 250.

The solid state light emitter 250 may be a flip chip Light EmittingDiode (LED). A light exit window of the flip chip LED is at a surfacethat faces away from the protrusion 202′. A surface of the flip chip LEDthat is opposite the light exit window is in contact with the protrusion202′ and partially extends beyond the protrusion. At the area thatextends beyond the protrusion the flip chip LED has electrical contactareas that are coupled to the above discussed electrical conductivetracks 260.

Although not shown in FIGS. 2a and 2b the body 104 of the light sourceassembly 100 may have an interface to couple a heat sink to near thecondensers 212, 212′. The heat sink interface may have a shapecorresponding to a specific surface of a heat sink such that the heatsink can be easily thermally coupled to the heat sink interface. Theheat sink interface may also comprise fastening elements to fasten theheat sink to the heat sink interface. The fastening elements may be abore to receive, for example, a screw, may be a protruding element with,for example, a thread. The fastening elements may also be hooks orlatches.

In FIG. 2b is also indicated a thickness th of the thermally conductivematerial that is in between the interface area 202 and the portion ofthe hollow space 210 that forms the evaporator 216. This thickness thshould be relatively small to obtain a good thermal coupling between thelight source and the evaporator 216. The thickness may be smaller than 2mm, optionally smaller than 1.5 mm, and optionally smaller than 1 mm.The thickness is chosen such that the thermal conductivity from theinterface area 202 towards the hollow space is larger than 3 W/mK.

FIG. 3a schematically shows a top-view of another embodiment of a lightsource assembly 300 comprising a light source cooling body. The lightsource assembly 300 is similar to the light source assembly 200,however, the hollow space 310 forms together with the wick 311 a loopheat pipe. Furthermore, as shown in FIG. 3b , the light source assembly300 comprises an optional arrangement of cooling fins 370.

As shown in the top-view, the hollow space 310 forms a loop. A region ofthe hollow space 310 near the interface area 202 is the evaporator 316and a region of the hollow space 310 that is away from the interfacearea 202 is the condenser 312. A portion of the loop is the vaporchannel 318 that transports the cooling material in the gaseous phasefrom the evaporator 316 to the condenser 312. Another portion of theloop is the liquid channel 319 that transports the cooling material inthe liquid phase from the condenser towards the evaporator 316. Theliquid channels 319 has, near the evaporator 316, a liquid reservoir 372for (temporarily) storing some cooling material in the liquid phase. Theevaporator 316 is provided with a wick 311 that has, in the specificembodiment of a loop heat pipe, a specific shapes that allows thetransport of cooling material in the liquid phase from the liquidchannel into the evaporator and that is configured to allow theevaporation of the cooling material at a surface of the wick 311 suchthat the evaporated cooling materials flows towards the vapor channel318.

Because the hollow space has only at one region a condenser 312, a body304 of the light source cooling body is smaller at the left side whenbeing compared to the embodiment of FIG. 2, which results also inshorter electrical conductive tracks 360 (and, thus, as can be seen inFIG. 3b , shorter dielectric tracks).

FIG. 3b schematically shows a cross-sectional view of the anotherembodiment of the light source assembly 300 of FIG. 3a along lineIII-III′. Only two cross-sections of the loop heat pipe formed by hollowspace 310 can be seen in FIG. 3b . Near the evaporator 316 the wick 311can be seen at the wall of the hollow space 310. Near the condenser 312,no wick 311 is present.

FIG. 3b also shows that the homogeneous body 304 of the light sourceassembly 300 may have an integral cooling fin structure 370. Integralmeans that, without any additional interface between the body 304 and,thus, the cooling fins, the body 304 and the cooling fin structure 370form a single component. Thus, as well as the body 304 and the coolingfin structure 370 are made of the thermally conductive material.Although the cooling fin structure 370 is drawn as a series of thinparallel arranged plates, the cooling fins of the structure 370 may haveany advantageous structure that allows the easy conduction of heat fromthe condenser 312 towards the environment of the light source assembly300. In the example of FIG. 3b , the cooling fin structure 370 is drawnat a specific side of the light source assembly 300 that is opposite thesurface where the light source 250 is thermally coupled to the interfacearea 202. However, in other examples, the cooling fins are provided at aside surface, or even at the side where the light source 250 isprovided. The shape of the cooling fin structure 370 is at leastselected such that light from the light source 250 can be easilytransmitted into the ambient of the light source assembly 300 withoutbeing significantly obstructed by the cooling fin structure 370.However, when some light impinges on the cooling fins, they may be madelight reflective to prevent the unwanted absorption of light.Additionally, it may be that the cooling fins fulfill a further role.The shape of a subset of the cooling fins may be adapted such that theyform an optical element for influencing or shaping a light beam emittedby the light source assembly 300. For example, the subset of the coolingfins may form a reflector, a collimator or a slat collimator. Thecooling fins that form an optical element may be provided with anadditional light reflective coating to better reflect the impinginglight. The additional light reflective coating may also be provided withan additive manufacturing technology.

FIG. 4a schematically shows a three dimensional view of a furtherembodiment of a light source assembly 400 comprising a light sourcecooling body. The body 404 of the light source cooling body iscircular/disk shaped. FIG. 4b schematically shows a cross-sectional viewof the further embodiment of FIG. 2a along line Iv-IV. As seen in FIG.4b , the body 404 is formed by a sort of disk that is arranged at thetop side (top side of FIG. 4b ) and has at its outer circumference asort of cylindrical wall extending in a downwards direction. Thiscylindrical wall comprises a large portion of the hollow space 410 andthis large portion forms the condenser 412. The disk shaped top portionhas in the middle an interface area to which a disk shaped light source450 is thermally coupled. Below this interface area the body 404 is alsothicker because it incorporates the evaporator 416 of the hollow space410. By means of the thick black line in FIG. 4a it has beenschematically presented what the trajectory of the hollow space isthrough the body 404. As seen in the cross-sectional view of FIG. 4b ,three portions of the hollow space 410 extend below the interface areato which the light source 450 is thermally coupled. In the cylindricalwall one single winding of the hollow space 410 isprovided—alternatively, more windings are provided in the cylindricalwall. The hollow space 410 comprises a wick 411 at its wall. In linewith the embodiment of FIG. 2b , this hollow space 410 with wick 411forms a (regular non-loop) heat pipe.

Please note in the case of FIGS. 4a and 4b all elements of the body 404,except of course the hollow space 410, form one integral homogenous body404. One thermally conductive material is used for the body 404 and thewick 411.

Optionally, the light source assembly 400 of FIG. 4 comprises coolingfins 470 that extend away from a surface to which also the light source450 is thermally coupled. The cooling fins 470 form, for example, areflector for shaping the beam emitted by the light source assembly 400.

In an alternative embodiment, the hollow space is arranged in adifferent manner inside the light source assembly. The hollow space maybe a meandering structure that meanders a plurality of times between aregion immediately in the neighborhood of the interface area and an areathat forms the condenser are (where the hollow space may deliver heat).The meandering structure may or may not form a loop. Such a hollow spaceforms a pulsating heat pipe when a cooling material, partly in theliquid phase, is provided in the hollow space. More information aboutthis type of heat pipes can be found in the article “Closed and openloop pulsating heat pipes” of Sameer Khandekar, et al, published in theproceedings of “13^(th) International Heat Pipe Conference” Shanghai,China, Sep. 21-25, 2004. The cited article is incorporated by reference.

FIG. 7a schematically shows an embodiment of a light source assembly 700comprising a light source cooling body. The light source cooling bodycomprises a homogenous body 704 made of single material and a hollowspace 710 that comprises an evaporator 716 and two condensers 712. Aportion of the hollow space 710 acts as a liquid reservoir 772 forholding a cooling material in the liquid phase. The evaporator 716comprises a wick structure 711 that transports by means of a capillaryaction liquid from the liquid reservoir 772 into the evaporator 716. Thewick structure 711 has at one side a wall that is in contact with thecooling material in the liquid phase. The wick structure 711 has alsofingers that extend from the wall away from the cooling material in theliquid phase into the evaporator 716. As is shown in FIG. 7b , theevaporator is arranged in the direct vicinity of the location wherelight sources are thermally coupled to the homogenous body. The heatthat is received from light sources evaporates the liquid in theevaporator. Because of the presence of the wick, the cooling material inthe gaseous phase can only move via the channels of the open space 710towards the condensers 712. The condensers are arranged away from theevaporator space and have, therefore, a lower temperature. The coolingmaterial in the gaseous phase may provide its heat to the homogeneousbody in the condenser and may condense towards the cooling liquid in theliquid phase. FIG. 7a present a sort of top view of the light sourceassembly 700 and it is to be noted that the presented view is a sort ofcutaway drawing in which the top layer (that comprises the interfacearea) of the light source assembly 700 is not drawn.

FIG. 7b schematically shows a cross-sectional view of the embodiment ofFIG. 7a along line VII-VII′. In the cross-sectional view the homogeneousbody 704 is shown in which an open space 710 is provided. Within theopen space is provided an evaporator 716 in which a which structure 711is present. At a left side of the wick structure 711 is a liquidreservoir 772 that may comprise a cooling material in the liquid phase.As discussed above, the wick structure 711 has a wall that is in contactwith the cooling material in the liquid phase. The wall extends from thebottom of the open space 710 towards the top surface of the open space710 and prevents that all cooling material in the liquid phase canuncontrollably flow into the evaporator 716. The wick structure 711allow the cooling material in the liquid phase to flow into theevaporator by a capillary action and, thus, in a controllable manner.The above discussed fingers of the wick structure 711 extend into theevaporator at one side of the open space 710. This one side is oppositethe side of the open space that is closest to the interface area. Theinterface area is close to the evaporator 716 and comprises a pluralityof protrusions 702′ on which Light Emitting Diodes (LEDs) 750 areprovided. The LEDs 750 are thermally coupled to the protrusions 702′. Ona surface of the homogeneous body 704 are provided electricallyconductive tracks 760 that provide power to the LEDs 750. Theelectrically conductive tracks 760 are electrically isolated from thehomogeneous body 704.

FIG. 5a schematically shows a light source assembly embodied in a lamp500. The lamp 500 comprises (not shown) a light source cooling bodyaccording to one of the previous embodiments of the light source coolingbody or comprises a light source assembly according to one of thepreviously discussed embodiments of the light source assembly.

FIG. 5b schematically shows a luminaire 550. The luminaire 550 compriseone or more light source cooling bodies according to the previouslydiscussed embodiments of the light source cooling bodies or comprisesone or more light source assemblies according to one of the previouslydiscussed embodiments of the light source assembly.

FIG. 6 schematically shows a method 602 of manufacturing a light sourcecooling body and a method 600 of manufacturing a light source assembly.

The method 602 of manufacturing a light source cooling body comprisesreceiving 610 a three dimensional model of a light source cooling bodythat comprises i) a hollow space comprising an evaporator and ancondenser, the hollow space being configured to hold a cooling materialpartially in a gaseous phase and partially in a liquid phase, a wall ofthe hollow space being formed by the thermally conductive material; ii)an interface area being arranged to thermally couple a light source toand configured to receive heat from the light source, wherein a) theinterface area being arranged in a direct vicinity of the evaporator andbeing separated by a thermally conductive wall from the evaporator forallowing heat of the light source to be transported towards theevaporator, b) the condenser being arranged away from the interface areawhere the light source cooling body has an interface to an environmentof the light source cooling body, and c) except the interface area, thelight source cooling body being a homogeneous body of the thermallyconductive material. The method 602 of manufacturing a light sourcecooling body further comprises building up 612 the light source coolingbody of a thermally conductive material by depositing layers on top ofeach other by means of an additive manufacturing technology according tothe received three dimensional model of the light source cooling body.

Examples of additive manufacturing technologies are, for example, directmetal laser sintering, selective laser sintering, electron beam melting,fused deposition modeling, 3d printing based on extrusion and additivemanufacturing based on using an arc wire. When such additivemanufacturing technologies are used, one can easily optimize the shapeof the light source cooling body and the shape of the hollow space.Traditionally, when heat pipes are used, the number of bends that can bemade in the heat pipes are limited because it would damage the internalstructure of the heat pipe too much, while with additive manufacturingthe internal structure may be optimized at every position—for example,the shape of the hollow space may be optimized and/or a design of thewick may be optimized. Also, the above manufacturing method builds upthe light source cooling body as a homogeneous component made of(optionally) one material. Thereby it is ensured that no interfaces arepresent in the light source cooling body with a relatively high thermalresistance. Thus, the manufacturing technology enables the manufacturingof light source cooling bodies which provide a better cooling of a lightsource. In an optional embodiment, the light source cooling body that isbuild up in layers is sintered.

The method 600 of manufacturing the light source assembly comprises themethod 602 of manufacturing the light source cooling body and at leastcomprises thermally coupling 630 a light source to the interface area.Optionally, the method 600 of manufacturing the light source assemblycomprises manufacturing 620 dielectric tracks of dielectric material onthe light source cooling body. The dielectric tracks extending towardthe interface area of the light source cooling body. Optionally, themethod 600 of manufacturing the light source assembly comprisesmanufacturing 622 power tracks of an electrically conductive material onthe dielectric tracks and providing, as part of the power tracks,connection areas at the interface area. The connection areas are forcoupling the light source to. When dielectric tracks and power tracksare manufactured, in the stage of thermally coupling 630 a light sourceto the interface area, the light source is also electrically connectedto the connection areas, for example, by soldering the light sourcepower contacts to the contacting areas. The manufacturing of theisolation tracks and the power tracks and/or the soldering of the lightsource to the power contacting areas may also be performed by usingadditive manufacturing technologies (such as 3d printing), optionally,in combination with locally heating the added material.

Manufacturing the dielectric tracks and/or the power tracks may beperformed with one of the subsequent technologies:3d-printing/dispensing of the respective materials at the requiredlocation, Laser Induced Forward Transfer (LIFT), aerosol spray coating,or 2d/3d plasma metallization.

It is to be noted that in FIG. 6a it seems that specific steps are to beexecuted in a specific order. The above discussed methods are notlimited to this order only. When appropriate, specific steps may beexecuted in another order, or in parallel to each other. For example, itmay be that in the additive manufacturing technology, as soon as asurface of the light source cooling body is manufactured to which thelight source may be thermally coupled and/or on which the dielectrictracks may be provided, the light source is already coupled to theinterface area and/or the dielectric tracks are manufactured (e.g. inparallel to manufacturing further layers of the light source coolingbody).

For example, the light source cooling body may be manufactured with oneof the above discussed additive manufacturing technologies, on thismanufactured light source cooling body the dielectric tracks (or layers)and the electrical conductive tracks may be manufactured/printed,subsequently solder bumps may be manufactured/printed, after which thelight source (e.g. Light Emitting Diode) is assembled to the interfacearea, subsequently a reflow soldering stage may be used to solder thelight source to the electrical conductive tracks, thereafter the hollowspace may be filled with the cooling material after which, finally, theopening to the hollow space is gas and liquid tightly sealed.Alternative, the light source cooling body may be manufactured with oneof the above discussed additive manufacturing technologies after whichthe hollow space may be filled with the cooling material after which theopening to the hollow space is gas and liquid tightly sealed, thereafterthe dielectric tracks (or layers) and the electrical conductive tracksmay be manufactured/printed, subsequently solder bumps may bemanufactured/printed, after which the light source (e.g. Light EmittingDiode) is assembled to the interface area, subsequently a reflowsoldering stage may be used to solder the light source to the electricalconductive tracks.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. Use of the verb “comprise” and itsconjugations does not exclude the presence of elements or steps otherthan those stated in a claim. The article “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.In the device claim enumerating several means, several of these meansmay be embodied by one and the same item of hardware. The mere fact thatcertain measures are recited in mutually different dependent claims doesnot indicate that a combination of these measures cannot be used toadvantage. Further, the invention is not limited to the embodiments, andthe invention lies in each and every novel feature or combination offeatures described above or recited in mutually different dependentclaims.

Embodiments of the cooling body, the light source assembly, theluminaire, the method to manufacture such cooling bodies and the methodto manufacture a light source assembly are defined in the subsequentnumbered clauses:

1. A light source cooling body (100), substantially the whole lightsource cooling body (100) being manufactured of the same thermallyconductive material, the light source cooling body (100) comprising:

a hollow space (210, 310, 410, 710) comprising an evaporator (116, 216,316, 416, 716) and a condenser (112, 212, 312, 412, 712), the hollowspace (210, 310, 410, 710) being configured to hold a cooling materialpartially in a gaseous phase and partially in a liquid phase, a wall ofthe hollow space (210, 310, 410, 710) being formed by the thermallyconductive material, at least a portion (114) of the hollow space (210,310, 410, 710) is tubular shaped, the hollow space (210, 310, 410, 710)further comprising a wick (211, 311, 411, 711) for transporting thecooling material in the liquid phase towards the evaporator (116, 216,316, 416, 716) for being evaporated when the evaporator (116, 216, 316,416, 716) receives heat, the wick (211, 311, 411, 711) beingmanufactured of the thermally conductive material,

an interface area (102, 202) being arranged to thermally couple with alight source (250, 450, 750) and arranged to receive heat from the lightsource (250, 450, 750), the interface area (102, 202) being an outerarea of the light source cooling body (100) arranged in a directvicinity of the evaporator (116, 216, 316, 416, 716) and being separatedby a thermally conductive wall from the evaporator (116, 216, 316, 416,716) for allowing heat of the light source (250, 450, 750) to betransported towards the evaporator (116, 216, 316, 416, 716),

wherein

the condenser (112, 212, 312, 412, 712) being arranged away from theinterface area (102, 202),

except the hollow space (210, 310, 410, 710), the light source coolingbody (100) being a homogeneous body (104, 304, 404, 704) of thethermally conductive material.

2. A light source cooling body (100) according to clause 1 furthercomprising cooling fins (370, 470) for providing a cooling interfacearea to ambient air, the condenser (112, 212, 312, 412, 712) beingarranged near the cooling fins (370, 470) for providing a thermal pathfrom the condenser (112, 212, 312, 412, 712) to the cooling fins (370,470), wherein the cooling fins (370, 470) are part of the homogeneousbody (104, 304, 404, 704) of the thermally conductive material.3. A light source cooling body (100) according to any one of thepreceding clauses, wherein a shape of the light source cooling body(100), and when referring to clause 2, optionally also a shape of thecooling fins (370, 470), is selected to allow a transmission of lightgenerated by a light source (250, 450, 750) towards an ambient of thelight source cooling body (100), wherein the light source (250, 450,750) is provided on the interface area (102, 202).4. A light source cooling body (100) according to any one of thepreceding clauses, wherein the interface area (102, 202) comprises aprotrusion (202′, 702′) having a flat surface facing away from the lightsource cooling body (100), wherein the flat surface is configured tothermally couple with a surface of a light source (250, 450, 750).5. A light source cooling body (100) according to any one of thepreceding clauses, wherein a thickness (th) of a thermally conductivewall between the interface area (102, 202) and the evaporator (116, 216,316, 416, 716) is thinner than 2 millimeter.6. A light source cooling body (100) according to any one of thepreceding clauses comprising a heat sink interface area arranged tothermally couple with a heat sink and configured to provide heat to theheat sink, the heat sink interface area being a further outside area ofthe light source cooling body (100) arranged close to the condenser(112, 212, 312, 412, 712) and optionally comprising connector elementsfor connecting a heat sink to the heat sink interface area.7. A light source cooling body (100) according to any one of thepreceding clauses, wherein the wall of the hollow space (210, 310, 410,710) is at least partially covered with the wick (211, 311, 411, 711)for transporting the cooling material in the liquid phase from thecondenser (112, 212, 312, 412, 712) towards the evaporator (116, 216,316, 416, 716).8. A light source cooling body (100) according to any one of thepreceding clauses, wherein the hollow space (210, 310, 410, 710) forms aloop in which a vapor channel (318) is provided from the evaporator(116, 216, 316, 416, 716) towards the condenser (112, 212, 312, 412,712) and a liquid channel (319) is provided from the condenser (112,212, 312, 412, 712) to the evaporator (116, 216, 316, 416, 716), thewick (211, 311, 411, 711) being arranged to receive cooling material inthe liquid phase from the liquid channel (319) or a liquid reservoir(372, 772) being fed by the liquid channel (319), the wick (211, 311,411, 711) at least extending into the evaporator (116, 216, 316, 416,716).9. A light source cooling body (100) according to any one of thepreceding clauses, wherein at least one of:

the thermally conductive material comprising at least one of Aluminum,Copper, Magnesium, Iron, Nickel, CrNi steel, Carbon steel, a Copper-Zincalloy, a Copper-Tin alloy, a thermally conducive plastic material, and athermally conductive ceramic material such as Aluminum Nitride, AluminumOxide, Beryllium Oxide, Boron Nitride, Silicon Carbide, Titanium Oxide,Magnesium Oxide, Zinc Oxide, Silicon Nitride, Zirconium Oxide, TungstenCarbide,

the cooling material comprising at least one of Water, Acetone, Ammonia,Methanole and Ethanole.

10. A light source assembly (200, 300, 400, 700) comprising:

the light source cooling body (100) according to any one of the clauses1 to 9,

a light source (250, 450, 750) provided on and being thermally coupledto the interface area (102, 202).

11. A light source assembly (200, 300, 400, 700) according to clause 10further comprising electric conductors (360, 760) being provided on andisolated from the light source cooling body (100) for providingelectrical power to the light source (250, 450, 750).12. A light source assembly (200, 300, 400, 700) according to clause 10or clause 11, wherein, when the light source cooling body (100) is alight source cooling body according to clause 2, a portion of thecooling fins (370, 470) are also arranged as an optical element forinfluencing, in use, a light beam emitted by the light source assembly(200, 300, 400, 700).13. A luminaire (550) comprising the light source cooling body (100)according to any one of the clauses 1 to 9 or comprising a light sourceassembly (200, 300, 400, 700) according to any one of the clauses 10 to12.14. Method (602) of manufacturing a light source cooling body, themethod comprising:

receiving (610) a three dimensional model of a light source cooling bodythat comprises i) a hollow space comprising an evaporator and ancondenser, the hollow space being configured to hold a cooling materialpartially in a gaseous phase and partially in a liquid phase, a wall ofthe hollow space being formed by the thermally conductive material, atleast a portion of the hollow space is tubular shaped, the hollow spacefurther comprising a wick for transporting the cooling material in theliquid phase towards the evaporator for being evaporated when theevaporator receives heat; ii) an interface area being arranged tothermally couple a light source to and configured to receive heat fromthe light source, wherein a) the interface area being arranged in adirect vicinity of the evaporator and being separated by a thermallyconductive wall from the evaporator for allowing heat of the lightsource to be transported towards the evaporator, b) the condenser beingarranged away from the interface area where the light source coolingbody has an interface to an environment of the light source coolingbody, and c) except the interface area, the light source cooling bodybeing a homogeneous body of the thermally conductive material,

building (612) up the light source cooling body of a thermallyconductive material by depositing layers on top of each other by meansof an additive manufacturing technology according to the received threedimensional model of the light source cooling body.

15. A method (600) of manufacturing a light source assembly, the methodcomprising the method (602) of manufacturing a light source cooling bodyaccording to clauses 14 and further comprising:

manufacturing (620) dielectric tracks of dielectric material on thelight source cooling body, the dielectric tracks extending toward theinterface area of the light source cooling body,

manufacturing (622) power tracks of an electrically conductive materialon the dielectric tracks and providing connection areas at the interfacearea, the connection areas are for electrically coupling the lightsource to,

thermally coupling (630) a light source to the interface area andelectrically connecting the light source to the connection areas.

The invention claimed is:
 1. A light source cooling body, substantiallythe whole light source cooling body being manufactured of the samethermally conductive material, the light source cooling body comprising:a hollow space comprising an evaporator and a condenser, the hollowspace being configured to hold a cooling material partially in a gaseousphase and partially in a liquid phase, a wall of the hollow space beingformed by the thermally conductive material, at least a portion of thehollow space is tubular shaped, the hollow space further comprising awick for transporting the cooling material in the liquid phase towardsthe evaporator for being evaporated when the evaporator receives heat,the wick being manufactured of the thermally conductive material; and aninterface area being arranged to thermally couple with a light sourceand arranged to receive heat from the light source, the interface areabeing an outer area of the light source cooling body arranged in adirect vicinity of the evaporator and being separated by a thermallyconductive wall from the evaporator for allowing heat of the lightsource to be transported towards the evaporator; wherein the condenseris arranged away from the interface area, wherein the hollow space isformed within the light source cooling body, the light source coolingbody being a planar homogeneous body of the thermally conductivematerial; wherein the interface area comprises a protrusion protrudingperpendicularly from the planar homogeneous body, the protrusion havinga flat surface facing away from the light source cooling body, whereinthe flat surface is configured to thermally couple with a surface of thelight source; wherein the hollow space forms a non-loop heat pipe; andwherein the wick extends from the condenser into the evaporator totransport the cooling material in the liquid phase from the condensertowards the evaporator.
 2. The light source cooling body according toclaim 1 further comprising cooling fins for providing a coolinginterface area to ambient air, the condenser being arranged near thecooling fins for providing a thermal path from the condenser to thecooling fins, wherein the cooling fins are part of the homogeneous bodyof the thermally conductive material.
 3. The light source cooling bodyaccording to claim 1, wherein a shape of the light source cooling bodyis selected to allow a transmission of light generated by the lightsource towards an ambient of the light source cooling body, wherein thelight source is provided on the interface area.
 4. The light sourcecooling body according to claim 1, wherein a thickness of a thermallyconductive wall between the interface area and the evaporator is thinnerthan 2 millimeter.
 5. The light source cooling body according to claim 1comprising a heat sink interface area arranged to thermally couple witha heat sink and configured to provide heat to the heat sink, the heatsink interface area being a further outside area of the light sourcecooling body arranged close to the condenser and optionally comprisingconnector elements for connecting a heat sink to the heat sink interfacearea.
 6. The light source cooling body according to claim 1, wherein atleast one of: the thermally conductive material comprises at least oneof Aluminum, Copper, Magnesium, Iron, Nickel, CrNi steel, Carbon steel,a Copper-Zinc alloy, a Copper-Tin alloy, a thermally conducive plasticmaterial, and a thermally conductive ceramic material such as AluminumNitride, Aluminum Oxide, Beryllium Oxide, Boron Nitride, SiliconCarbide, Titanium Oxide, Magnesium Oxide, Zinc Oxide, Silicon Nitride,Zirconium Oxide, Tungsten Carbide, or the cooling material comprises atleast one of Water, Acetone, Ammonia, Methanole and Ethanole.
 7. Thelight source cooling body according to claim 1, wherein the light sourcecooling body is part of a light source assembly, the light sourceassembly comprising a light source provided on and being thermallycoupled to the interface area.
 8. The light source cooling bodyaccording to claim 7, wherein the light source assembly furthercomprises electric conductors being provided on and isolated from thelight source cooling body for providing electrical power to the lightsource.
 9. The light source cooling body according to claim 7,comprising cooling fins that are arranged as an optical element forinfluencing, in use, a light beam emitted by the light source assembly.10. The light source cooling body according to claim 7, wherein thelight source is a flip chip Light Emitting Diode being provided on theprotrusion, a light exit window of the flip chip Light Emitting Diodefaces away from the flat surface of the protrusions, the flip chip LightEmitting Diode has an opposite surface opposite the light exit window, aportion of an opposite surface is provided on the flat surface andanother portion of the opposite surface extends beyond the protrusionand comprises electrical contact areas.
 11. A luminaire comprising thelight source cooling body according to claim
 1. 12. A method ofmanufacturing a light source cooling body, the method comprising:receiving a three dimensional model of a light source cooling body thatcomprises i) a hollow space comprising an evaporator and an condenser,the hollow space being configured to hold a cooling material partiallyin a gaseous phase and partially in a liquid phase, a wall of the hollowspace being formed by the thermally conductive material, at least aportion of the hollow space is tubular shaped, the hollow space furthercomprising a wick for transporting the cooling material in the liquidphase towards the evaporator for being evaporated when the evaporatorreceives heat; ii) an interface area being arranged to thermally couplea light source to and configured to receive heat from the light source,wherein a) the interface area being arranged in a direct vicinity of theevaporator and being separated by a thermally conductive wall from theevaporator for allowing heat of the light source to be transportedtowards the evaporator, b) the condenser being arranged away from theinterface area where the light source cooling body has an interface toan environment of the light source cooling body, c) except the interfacearea, the light source cooling body being a planar homogeneous body ofthe thermally conductive material wherein the hollow space is formedwithin the planar homogenous body, and, d) the interface area comprisesa protrusion protruding perpendicularly from the planar homogeneousbody, the protrusion having a flat surface facing away from the lightsource cooling body, the flat surface being configured to thermallycouple with a surface of the light source; building up the light sourcecooling body of a thermally conductive material by depositing layers ontop of each other by means of an additive manufacturing technologyaccording to the received three dimensional model of the light sourcecooling body; wherein the hollow space forms a non-loop heat pipe; andwherein the wick extends from the condenser into the evaporator totransport the cooling material in the liquid phase from the condensertowards the evaporator.
 13. The method of manufacturing a light sourceassembly, the method comprising the method of manufacturing a lightsource cooling body according to claim 12 and further comprising:manufacturing dielectric tracks of dielectric material on the lightsource cooling body, the dielectric tracks extending toward theinterface area of the light source cooling body, manufacturing powertracks of an electrically conductive material on the dielectric tracksand providing connection areas at the interface area, the connectionareas are for electrically coupling the light source to, thermallycoupling a light source to the interface area and electricallyconnecting the light source to the connection areas.
 14. An apparatuscomprising, comprising: a light source cooling body; a non-loop heatpipe within the light source cooling body comprising an evaporator and acondenser, the non-loop heat pipe being configured to hold a coolingmaterial partially in a gaseous phase and partially in a liquid phase;an interface area arranged to thermally couple with a light source andarranged to receive heat from the light source, the interface area beingan outer area of the light source cooling body arranged in a directvicinity of the evaporator and being separated by a thermally conductivewall from the evaporator for allowing heat of the light source to betransported towards the evaporator; and a wick that extends from thecondenser into the evaporator to transport the cooling material in theliquid phase from the condenser towards the evaporator; and wherein thecondenser is arranged away from the interface area, wherein theinterface area comprises a protrusion protruding perpendicularly fromthe homogeneous body, the protrusion having a flat surface facing awayfrom the light source cooling body, wherein the flat surface isconfigured to thermally couple with a surface of the light source,wherein the non-loop heat pipe is made of the thermally conductivematerial and is integrated within the light source cooling body, thelight source cooling body being planar.
 15. The apparatus according toclaim 14, wherein the light source cooling body is formed from athermally conductive material.
 16. The apparatus according to claim 14,further comprising cooling fins for providing a cooling interface areato ambient air, the condenser being arranged near the cooling fins forproviding a thermal path from the condenser to the cooling fins, whereinthe cooling fins made of the thermally conductive material.
 17. Theapparatus according to claim 14, wherein a shape of the light sourcecooling body is selected to allow a transmission of light generated bythe light source towards an ambient of the light source cooling body,wherein the light source is provided on the interface area.
 18. Theapparatus according to claim 14, wherein a thickness of a thermallyconductive wall between the interface area and the evaporator is thinnerthan 2 millimeter.
 19. The apparatus according to claim 14, furthercomprising a heat sink interface area arranged to thermally couple witha heat sink and configured to provide heat to the heat sink, the heatsink interface area being a further outside area of the light sourcecooling body arranged close to the condenser and optionally comprisingconnector elements for connecting a heat sink to the heat sink interfacearea.
 20. The apparatus according to claim 14, wherein the thermallyconductive material comprises at least one of Aluminum or Copper, andthe cooling material comprises Water.